隔热结构中非晶硅的释H_2机理与工艺研究

对采用等离子增强化学气相淀积法(PECVD)制备的氢化非晶硅(a-Si:H)薄膜进行了退火释H2实验,并对三文治结构膜层生长工艺作了改进。红外透射光谱表明:提高退火温度及增加退火时间会造成Si-H键断裂释放H2影响器件结构完整;不断改进设计,最终采用精简有效热敏面积及将退火工艺提前以扩张释H2渠道的方案,获得600℃退火后仍保持完整三文治结构的优化设计流程。     

溶胶-凝胶旋涂法制备ITO薄膜

以InCl_3和SnCl_4·5H_2O为主要原料,采用溶胶-凝胶法和旋转涂膜工艺,在普通玻璃基片上制备掺锡氧化铟(ITO)纳米透明导电薄膜。应用X射线衍射(XRD)、扫描电子显微镜(SEM)对薄膜进行表征;研究了不同热处理温度、热处理时间及不同旋转速度对薄膜形态和结构的影响。结果表明,采用溶胶-凝胶旋涂法制备的ITO薄膜是由立方相纳米颗粒构成,随涂层增加,薄膜表面变得平滑。随热处理温度的提高或时间的延长,薄膜由非晶态逐渐转化为良好的晶态薄膜。     

Structural characteristics of as-deposited and crystallized mixed-phase silicon films

In this work, we report on the structural characteristics of as-deposited and crystallized mixed-phase silicon films prepared by thermal decomposition of silane in a low pressure chemical vapor deposition reactor. Mixed-phase films consist of crystallites embedded in an amorphous matrix. The size of these crystallites depends upon the surface diffusion length, a parameter quantitatively expressing the potential of adsorbed silicon atoms for surface diffusion. The density of the pre-existing crystallites can be related to the maximum density of critical nuclei, which develops during the deposition of the film. Both variables were quantitatively related to the deposition temperature and rate via physical models reflecting the experimental observations. Values for the parameters associated with these models were extracted by fitting the experimental data to the theoretical equations. Our theoretical analysis is the first to relate quantitatively the structural characteristics of as-deposited mixed-phase films to the prevailing deposition conditions. Mixed-phase films can crystallize in a much shorter time than as-deposited amorphous films, due to the combination of the growth of the pre-existing crystallites and the higher nucleation rate of new crystallites within the amorphous matrix of the mixed-phase film. The crystallization time and final grain size of crystallized mixed-phase films were found to decrease with increasing density of pre-existing crystallites. However, we showed that if composite films are deposited, consisting of a mixed-phase layer and an amorphous layer, the grain size after crystallization could be comparable to that of crystallized as-deposited amorphous films, with the crystallization time of such composite films about threefold shorter. The structure of both as-deposited and crystallized single and composite mixed-phase films was found to be identical for films deposited on both oxidized silicon and Corning Code 1735 glass substrates.     

Effect of annealing on physical properties of CBD synthesized nanocrystalline FeSe thin films

Nanocrystalline FeSe thin films were successfully prepared by solution growth method using ferric chloride and sodium selenosulphate as cationic and anionic precursors along with complexing agent oxalic acid. The thickness dependent physical properties of FeSe thin films prepared by varying deposition time are discussed. The FeSe films of thickness 161 nm were further annealed to investigate its impact on physical properties. The X-ray diffraction studies showed that, as deposited FeSe films are nano crystalline in nature and their crystallinity increases with thickness as well as with annealing temperature. The morphological studies showed that FeSe exhibits granular surface with channel like features at higher thickness. The electrical resistivity and thermo-emf measurements confirmed that, FeSe films are semiconducting in nature with P-type conductivity. The activation and band gap energies of FeSe films are found dependent on film thickness as well as on annealing temperature.     

酞菁染料薄膜的光存贮特性

本文研究了酞菁分子结构与光存贮性能的关系，给出作用在酞菁薄膜上的激光功率和辐照时间，其阈值随酞菁分子侧链的增长而增加的特性。     

三束飞秒激光辐照下铜膜内电子非平衡热输运

首先采用有限元法数值计算了铜膜内的电子温度和晶格温度分布变化,揭示了铜膜内电子非平衡热输运时间随飞秒激光光束参量的变化情况。仿真结果表明,铜膜内的电子非平衡热输运时间会随着泵浦光束数量及脉冲能量密度的增加而增加,并且使用三束飞秒泵浦激光作用时,电子非平衡热输运时间比单脉冲作用时的电子非平衡热输运时间增加了3倍。其次使用三束飞秒激光泵浦的泵浦-探测实验系统进行验证。实验结果表明:通过用具有一定延时的三束飞秒泵浦激光作用铜膜时,铜膜表面的瞬态反射率出现三次突变,使电子非平衡热输运时间得到极大延长,从而大幅度消除激光加工热障,并提高加工的质量、精度和效率。     

衬底温度对SnO2薄膜中激光感生电压效应的影响

采用固相反应法制备了四方相结构的SnO2靶材,选用蓝宝石衬底,利用脉冲激光沉积法在不同温度下生长了一系列SnO2薄膜。X射线衍射测试结果表明,SnO2薄膜具有四方金红石结构,并且沿a轴近外延生长。另外,在倾斜衬底上生长的SnO2薄膜上观察到了激光感生电压(LIV)效应,并研究了衬底温度对SnO2薄膜中LIV效应的影响。结果表明,随着生长温度从500℃增加到800℃,SnO2薄膜中的LIV信号的峰值电压先增加后减小,响应时间随衬底温度的升高先降低后增加,此外,存在一个最佳的衬底温度,使得SnO2薄膜的LIV信号的峰值电压达到最大,响应时间达到最小。在生长温度为750℃的SnO2薄膜中探测到响应最快的LIV信号,在紫外脉冲激光辐照下,峰值电压约为4V,响应时间为98ns,信号的上升沿为28ns,与激光的脉宽相当。     

退火工艺对La-Nb共掺杂Bi_4Ti_3O_(12)薄膜结构的影响

采用sol-gel法制备了Si基Bi3.25La0.75Ti2.94Nb0.06O12.03(BLTN)铁电薄膜,研究了退火温度、升温速率和退火时间对BLTN薄膜微观结构的影响。结果表明:制备的BLTN薄膜具有单一的钙钛矿结构,且为随机取向,表面平整致密;退火温度由550℃升高到750℃时,薄膜的衍射峰强度增强,晶粒尺寸由65 nm增大到110 nm;退火升温速率由10℃/min提高为20℃/min时,薄膜的晶化程度降低;退火时间对薄膜的晶相结构影响不大,但时间超过30 min会造成薄膜表面孔洞增多、致密性下降。     

不同沉积方式SiO2薄膜的自然时效特性

SiO2薄膜是光学薄膜领域内常用的重要低折射率材料之一。文中采用不同沉积技术在Si基底上制备了SiO2薄膜,并研究了它们光学特性的自然时效特性。采用不同贮存时间的椭偏光谱表征SiO2薄膜的光学特性,随着时间的增加,EB-SiO2薄膜和IAD-SiO2薄膜的物理厚度和光学厚度随着增加,但IBS-SiO2薄膜随着减小,变化率分别为1.0%,2.3%和-0.2%。当贮存时间达到120天时,IBS-SiO2薄膜、EB-SiO2薄膜和IAD-SiO2薄膜的物理厚度和光学厚度趋于稳定。实验结果表明,IBS-SiO2薄膜的光学特性稳定性最好,在最外层保护薄膜选择中,应尽可能选择离子束溅射技术沉积SiO2薄膜。     

The effects of thermal nitridation conditions on the reliability of thin nitrided oxide films

MIS capacitors on n-type silicon substrate with thin oxide films thermally nitrided in NH3gas ambient at different temperatures and for different times have been fabricated. The effects of nitridation temperature and time on the properties of the thin nitrided oxide films have been examined and analyzed by using a constant current stress. It is found that the oxide films nitrided at 900°C exhibit much improved total charge to breakdown and interface trap generation if proper nitridation time is used. The superior characteristics of the fabricated nitrided oxide films using the proposed optimum conditions are suitable for existing CMOS/VLSI applications.     

微波辅助化学浴沉积法制备ZnO薄膜

采用微波辅助化学浴沉积法在玻璃衬底上制备了氧化锌(ZnO)薄膜。初步探讨了化学浴沉积法制备ZnO薄膜的反应机理。X射线衍射分析结果表明所得的ZnO薄膜为六方纤锌矿结构的多晶薄膜,不具有任何晶面的择优生长取向;随着反应时间从15min延长至30min,薄膜结晶性能提高,晶粒尺寸从27nm长大到73nm。扫描电子显微镜分析显示反应沉积12min时,薄膜比较均匀、致密,无裂纹出现;反应沉积25min后,薄膜厚度增加,同时出现开裂现象。     

光敏性溶胶-凝胶波导材料

采用有机改性硅酸盐制备了光敏性溶胶 凝胶 ,并应用四丙氧基锆作为调节折射率的材料 .为了增加薄膜与硅片的粘附作用 ,先用干氧热氧化法在硅片上生长一层厚度约为 15 0nm的SiO2 ,然后使用提拉法在硅片上提拉成膜 ,薄膜厚度达到 3 6 μm .研究发现紫外曝光时间和坚膜时的后烘温度都会使薄膜的折射率增大 .样品的原子力显微镜照片表明薄膜的表面非常平整 ,在 5 μm× 5 μm的范围内表面起伏只有 0 6 5 7nm .利用波导阵列掩膜版 ,对制备的薄膜在紫外光波段下曝光 ,得到了表面平坦、侧墙光滑、陡直的沟道波导阵列 .     

Characterization of sputtered ZnO films under different sputter-etching time of substrate

Polycrystalline ZnO films are prepared using radio frequency magnetron sputtering on glass substrates which are sputteretched for different time. Both the size of ZnO grains and the root-mean-square (RMS) roughness decrease, as the sputteretching time of the substrate increases. More Zn atoms are bound to O atoms in the films, and the defect concentration is decreased with increasing sputter-etching time of substrate. Meanwhile, the crystallinity and c-axis orientation are improved at longer sputter-etching time of the substrate. The Raman peaks at 99 cm⁻¹, 438 cm⁻¹ and 589 cm⁻¹ are identified as E₂(low), E₂(high) and E₁(LO) modes, respectively, and the position of E₁(LO) peak blue shifts at longer sputter-etching time. The transmittances of the films, which are deposited on the substrate and etched for 10 min and 20 min, are higher in the visible region than that of the films deposited under longer sputter-etching time of 30 min. The bandgap increases from 3.23 eV to 3.27 eV with the increase of the sputter-etching time of substrate.     

掺Al的纳米Si-SiO2复合薄膜的光学非线性特性

采用时间分辨四波混频方法,用钛宝石飞秒激光器测量了掺Al的纳米Si-SiO2复合薄膜的光学非线性特性.得到薄膜非共振三阶非线性极化系数为1.0×10-10esu,弛豫时间为60fs.分析认为薄膜的光学非线性增强来源于SiO2镶嵌的纳米Si中电子的量子限制效应,而不是来源于Al杂质,这是因为Al易被氧化,薄膜中没有形成Al团簇.     

掺Al的纳米Si-SiO2复合薄膜的光学非线性特性

采用时间分辨四波混频方法,用钛宝石飞秒激光器测量了掺Al的纳米Si-SiO2复合薄膜的光学非线性特性.得到薄膜非共振三阶非线性极化系数为1.0×10-10esu,弛豫时间为60fs.分析认为薄膜的光学非线性增强来源于SiO2镶嵌的纳米Si中电子的量子限制效应,而不是来源于Al杂质,这是因为Al易被氧化,薄膜中没有形成Al团簇.     

Ultrasonic experiments with lead zirconate titanate thin films fabricated by sol gel processing

Surface and bulk acoustic wave measurements with lead zirconate titanate (PZT) thin films fabricated by a sol gel processing technique are reported for the first time. The piezoelectricity of such films was achieved by poling. Good acoustic properties of these films are confirmed by the acoustic images and V(z) curves obtained by a scanning acoustic microscope.<>     

红外敏感硫化铅薄膜的化学机理探讨

硫化铅(PbS)薄膜光电性能的好坏决定了探测器的性能水平。PbS薄膜是制作PbS红外探测器的核心和基础,也是一直以来PbS探测器改进和提高的研究方向。分析了高温法、柯达法和联氨法共3种化学工艺形成硫化铅膜的反应机理。结果表明,光敏薄膜都涉及到PbSO4的形成。X-RD衍射测试结果证明硫化铅多晶薄膜中存在PbSO4,因此提出含有低浓度PbSO4的PbS固溶体的形成是光敏薄膜具有光敏特性的原因之一。     

Charge trapping in silicon-rich Si3N4 thin films

Silicon-rich silicon nitride (SRN) films were grown by low pressure chemical vapour deposition (LPCVD) with excess silicon concentrations varying from 8.8 to 12.8%. All films were found to be predominantly -Si₃N₄ with free silicon crystallites being found in the films with the greatest silicon content.

MIS capacitors were fabricated from the films and transient flat band measurements were performed on these devices. For positive (negative) applied bias voltages, the flat band shift was in a positive (negative) direction implying a net increase in negative (positive) charge within the SRN film. A logarithmic time dependence was found for the transient flat band shift while for long periods of time (i.e. t > 1 s) the curren transient was found to be inversely proportional to time. A charge trapping model is presented which predicts a logarithmic increase in the flat band shift with time. The model is based on the simple assumption that there is electron tunnelling between the silicon valence and conduction bands and the deep defect levels in the SRN films. Very good agreement was found between the data and the model for low electric fields. At high fields, the situation becomes complicated by other transport processes which lead to a saturation of the flat band shift with time. The current transients are similarily affected. For these SRN films the density of trapping centres near the SRN-silicon interface was found to be of the order of 3 × 10¹⁹ cm⁻³.     

Transformations of porous layers upon high-temperature annealing: Simulation

In this work, the lattice kinetic Monte Carlo model has been used to investigate morphological transformations in porous films of different density in the process of high-temperature annealing. The characteristics of porous films of different initial densities have been compared at different time moments of the sintering process. Layers with a porosity from 20% to 50% having a cubic lattice have been studied. It is shown that closed pores are formed in the film if the porosity is less than 25%; in films with a larger porosity, percolation pores arise. It has been established that the rate of sintering depends on the annealing time nonmonotonically.     

复合效应对掺杂氧化物透明导电薄膜的影响

首次引入复合效应对不同价态差的掺杂氧化物透明导电（TCO）薄膜的载流子浓度及其迁移率进行了分析。对于较高温下制备的TCO薄膜,对载流子迁移率起主要作用的散射机制是带电离子散射和电中性复合粒子散射。带电离子散射迁移率与带电离子的有效电荷数大致呈反比关系,在载流子浓度相同的情况下,随着复合几率增大,价态差分别为3和4的TCO薄膜中的带电离子的平均有效电荷分别趋于1和2,因此带电离子散射迁移率也随之增大,分别趋于价态差为1和2的TCO薄膜的带电离子散射迁移率。而对于价态差为3的TCD薄膜,由于电中性复合粒子的数量较少,对载流子的散射最弱,因此在复合几率较大的情况下,价态差为3的TCO薄膜有可能获得比价态差为1的TCO薄膜更高的载流子迁移率。